The problem with dwg2dxf is that it needs the non-free OpenDWG library which you need to buy from OpenDWG.

Reading DWG files has been declared a high-priority GNU project and a library called libreDWG is coming along nicely. This library can already turn quite complex DWG files into SVGs, and seems to work for the DWG files I got from my Architect.

However this is of course of limited use to QCAD users as we can't import or export SVG either.

I have no idea if newer QCAD releases plan to use libreDWG? I would very much like to take a look at adding support for it, but am short of time and no expert in either codebase.

Is upstream already looking at this and is anyone else interested in this?

I intend to package libreDWG for Debian which will be a start, and hopefully software like QCAD will start to use it.

OK, glad to hear that there is progress on this as not having DWG access is pretty limiting these days, as I'm sure you are aware.
However the Open Design Alliance libraries are not freely redistributable, (unless the licencing has changed recently), nor are the libraries themselves available for download for individuals. As a Linux user I can read the spec or download a windows utility. This doesn't help write free software CAD applications at all.

If QCAD uses these libraries then it will cease to be freely redistributable in Debian, as it would then depend on non-free software. Now you have a business to run and having taken out an ODA licence I guess using those libraries makes sense for you. I assume they are rather more mature than libreDWG is?

However for the free version it would be much better to use the libreDWG libraries even if they aren't quite as good yet, as then QCAD remains free software that can be built and run on all architectures, and distributed by Debian and its derivatives.

I don't know if it is easy to keep this option of using the alternative library open or if that introduces complexity to the codebase that you don't wish to support? Hopefully the API of the two libraries is not too dissimilar. Having no access to the ODA libs I have no way of knowing.

Have you looked into libreDWG yet? I have found the responsiveness of the authors to be remarkable and they are eager to have test cases that don't yet work right. http://www.gnu.org/software/libredwg/

I'm sure they would be extremely grateful for any insight/feedback you could provide as someone with great experience in this area, and being pretty much the exact person they are hoping is their userbase :-)

QCAD 3 can also be built without the OpenDesign libraries as they are only required by the DXF/DWG import / export filters, so a future community edition of QCAD could have no DWG support or use an alternative library indeed.